1. Field of the Invention
The present invention relates to a steam trap to automatically discharge condensate generated in various kinds of steam using equipment and steam pipe lines; and more particularly, to a thermally-actuated steam trap adapted to discharge the condensate below a desired temperature out of a system by using a temperature control element including medium which is heated and cooled by steam and condensate, and expanded and contracted in accordance with the temperature thereof.
2. Description of the Prior Art
The basic construction of a thermally-actuated steam trap has been well-known, as disclosed in, for example, Japanese examined patent publication No. 60-46318. As understood from this publication, the thermally-actuated steam trap comprises a temperature control element obtained by filling expansible medium in an inner space formed by securing the outer peripheral edges of a disk-like wall member and a diaphragm to each other, a valve chest communicating with an inlet in which the temperature control element is provided, a valve member connected to the diaphragm, provided in the valve chest and driven by employing the expansion and contraction of the expansible medium and a valve seat member having a discharge passage through which the valve chest communicates with an outlet, on and from which the valve member is seated and separated.
When the steam of high temperature enters the valve chest, the expansible medium expands, so that the valve member is seated on the valve seat member to thereby close the discharge passage. Accordingly, the discharge of the steam is prevented. When the condensate of low temperature enters, the expansible medium is contracted and the valve member is separated from the valve seat member to thereby open the discharge passage. Thus, the condensate is discharged out of a system.
However, in the thermally-actuated steam trap of such a type, in the case where the temperature control element is broken and the expansible medium flows out, the valve member is seated on the valve seat member due to the fluid pressure of the inlet side to thereby close the discharge passage. When the valve member closes the passage upon the breakage of the temperature control element, such problems may arise that the condensate cannot be discharged; and therefore, the operating efficiency of steam using equipment is deteriorated, defective articles are produced or water hammer phenomenon is caused, which results in broken equipment or pipelines.